double oven and hob off same supply

[darren bergin]

this is what i have electric cooker and hob

40a rcbo at consumer unit
6mm twin and earth feeding ccu (type with 13a socket on it)
cable is about 5 metres long clipped direct to joists
double oven says it rated at 20 amps
hob 6kw

oven and hob are both fed with individual 4mm cables from cooker connection unit

Is this set up ok????

 

[ColJack]

thanks to a little thing we call diversity, your load works out to..

46A total

diversity is 10A + 30% of the remainder, +5A for a socket outlet on the switch..

so, 10+ (30%x36 ) +5 = 25.8A

diversity allows for the fact that not every ring and element in the oven will be on at the same time..

 

[ericmark]

this is what i have electric cooker and hob

40a rcbo at consumer unit
6mm twin and earth feeding ccu (type with 13a socket on it)
cable is about 5 metres long clipped direct to joists
double oven says it rated at 20 amps
hob 6kw

oven and hob are both fed with individual 4mm cables from cooker connection unit

Is this set up ok????

Yes for 6mm clipped direct 47A but no for 4mm cable only rated 37A clipped direct. So it would need the 4mm replacing with 6mm or fit 32A rcbo 6kw = 26A so with oven at 20A that's 46A but with diversity it would likely work on a 32A rcbo.

So in all it does not comply and some alteration is required.

Why do you ask

 

[darren bergin]

so all works out great

because i had a look at hob and oven connections and there is absolutely no way in this world i can see 6mm cables gettin in the terminals

 

[darren bergin]

remember the 4mm is only feeding appliances from ccu
like i say no way would 6mm fit into hob nor oven terminals!!
obviously why 4mm was used in first place as far as i can see...

 

[ColJack]

4mm is fine given that the load is limited to 20A on one and 26A on another..

 

[sparkyspike]

4mm is fine given that the load is limited to 20A on one and 26A on another..

How is the load limited?

 

[ColJack]

hmm lets see...

thermostats in the oven and hob for one, another would be the thermal cutouts if they got too hot, another would be a known length and resistance range of the elements

it's a fixed load..

same as a 100W light bulb is a fixed load..

 

[darren bergin]

Can i just say ..just found out .,answers above are wrong because at the end of the day there is a 40a rcbo at cu and 4mm feeding appliances from ccu .......... the breaker cannot be used in this situation ... 4mm cable on 40a cb 4mm cable clipped direct can only handle 37a